Hybrid image potential states in molecular overlayers on graphene

Sasfan Arman Wella,Ikutaro Hamada,Nana Kawaguchi,Kouji Inagaki,Yoshitada Morikawa,Hiroyuki Sawada,Yuji Hamamoto,Fahdzi Muttaqien

doi:10.1103/physrevmaterials.1.061001

Sasfan Arman Wella, Ikutaro Hamada + Show 6 more

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https://doi.org/10.1103/physrevmaterials.1.061001

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Abstract

The structural and electronic properties of naphthalene adsorbed on graphene are studied from first principles using the van der Waals density functional method. It is shown that naphthalene molecules are stabilized by forming a superstructure with the periodicity of $(2\sqrt{3}\ifmmode\times\else\texttimes\fi{}2\sqrt{3})$ and a tilted molecular adsorption geometry on graphene, in good agreement with the scanning tunneling microscopy (STM) experiments on highly oriented pyrolytic graphite. Our results predict that image potential states (IPSs) are induced by intermolecular interaction on the naphthalene overlayer, hybridizing with the IPSs derived from graphene. The resultant hybrid IPSs are characterized by anisotropic effective mass reflecting the molecular structure of naphthalene. By means of STM simulations, we reveal that one of the hybrid IPSs manifests itself as an oval protrusion distinguishable from naphthalene molecular orbitals, which identifies the origin of an experimental STM image previously attributed to the lowest unoccupied molecular orbital of naphthalene.

Highlights

Hybrid image potential states in molecular overlayers on grapheneSasfan Arman Wella, Hiroyuki Sawada, Nana Kawaguchi, Fahdzi Muttaqien, Kouji Inagaki, Ikutaro Hamada, Yoshitada Morikawa, and Yuji Hamamoto1,*
The emergence of image potential states (IPSs) is a universal nature of metal surfaces, characterized by a set of unoccupied states quantized to a Rydberg series analogous to the hydrogen atom [1,2]
By means of scanning tunneling microscopy (STM) simulations, we reveal that one of the hybrid IPSs manifests itself as an oval protrusion distinguishable from naphthalene molecular orbitals, which identifies the origin of an experimental STM image previously attributed to the lowest unoccupied molecular orbital of naphthalene

Summary

Hybrid image potential states in molecular overlayers on graphene

Sasfan Arman Wella, Hiroyuki Sawada, Nana Kawaguchi, Fahdzi Muttaqien, Kouji Inagaki, Ikutaro Hamada, Yoshitada Morikawa, and Yuji Hamamoto1,*. The structural and electronic properties of naphthalene adsorbed on graphene are studied from first principles using the van der Waals density functional method√. It is s√hown that naphthalene molecules are stabilized by forming a superstructure with the periodicity of (2 3 × 2 3) and a tilted molecular adsorption geometry on graphene, in good agreement with the scanning tunneling microscopy (STM) experiments on highly oriented pyrolytic graphite. Our results predict that image potential states (IPSs) are induced by intermolecular interaction on the naphthalene overlayer, hybridizing with the IPSs derived from graphene. By means of STM simulations, we reveal that one of the hybrid IPSs manifests itself as an oval protrusion distinguishable from naphthalene molecular orbitals, which identifies the origin of an experimental STM image previously attributed to the lowest unoccupied molecular orbital of naphthalene

Introduction

Published by the American Physical Society

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